A reevaluation of the role of the catecholamines norepinephrine (NE) and dopamine (DA) in self stimulation behavior (and by inference, positive reinforcement) forms the primary focus of the present proposal. Attention is also given to the possible role of catecholamines in mediating neural events and behaviors relating to hunger, thrist, and sex drives. Chronic depletion of whole brain CA levels will be accomplished by intraventricular injection of 6-hydroxydopamine (6-OH DA). The same compound will also be applied to specific intracerebral tissue in order to lesion specific catecholamine pathways. Appropriate pharmacological manipulations will be used across a number of studies to foster either selective depletion of NE or DA or a more massive depletion of both compounds following 6-OH DA treatment. An assessment of the role played by receptor supersensitivity in abetting early and/or later recovery of functions following 6-OH DA depletion of catecholamines will also be attempted. Acute acting drugs which specifically deplete NE or DA will be used in conjunction with amphetamine in attempts to evaluate the contribution of each catecholamine to amphetamine induced facilitation of self-stimulation behavior. Finally an entire section devoted to developmental studies attempts to evaluate the effects of early, chronic depletion of brain catecholamines on later self stimulation behavior and on measures related to hunger, thirst, and sexual drives throughout the developmental period and early adulthood. Biochemical assays will be used to evaluate the effectiveness of all drug treatments employed in producing appropriate levels of depletion of DA and/or NE.